Vehicle telephone system

ABSTRACT

A telephone system for a vehicle comprising: a vehicle transceiver, on board said vehicle, and connectable to a cellular telephone network for bi-directional communication therewith; a server terminal, on board said vehicle, connected to said transceiver and having an identification address; a plurality of user terminals, distributed on board the vehicle, each capable of accepting an identity of a user of the cellular telephone system and each connected to said server terminal whereby a plurality of users may communicate simultaneously with said network via the server terminal; and a location data base for identifying users of the cellular telephone system when their identifies are accepted by respective user terminals and for associating those users with said identification address to permit communication to be established between those users and the cellular telephone system via the server terminal.

The present invention relates to a telephone system for use in avehicle, which is applicable to cellular telephone systems such as GSMor DCS cellular systems and U.S. standard systems.

It is known that RF mobile telephones using cellular networks are notgenerally used in aircraft due to the belief that there is thepossibility of interference with aircraft equipment.

It is also known that generally only fixed line systems are installedinto aircraft. These fixed line systems are capacity limited so that thenumber of calls to and from an aircraft at any one time is limited to afew simultaneous calls.

Furthermore as any vehicle which has a satellite communication system,as the vehicle moves from a region of coverage provided by one satelliteto that of another all calls must be individually “handed over”. Thiscan lead to calls being dropped.

It is an object of the present invention to at least partly mitigate theabove problems.

According to the present invention there is provided a telephone systemfor a vehicle comprising a vehicle transceiver, on board said vehicle,and connectable to a cellular telephone network for bi-directionalcommunication therewith, a server terminal, on board said vehicle,connected to said transceiver and having an identification address, aplurality of user terminals, distributed on board the vehicle, eachcapable of accepting an identity of a user of the cellular telephonesystem and each connected to said server terminal whereby a plurality ofusers may communicate simultaneously with said network via the serverterminal, and a location data base for identifying users of the cellulartelephone system when their identifies are accepted by respective userterminals and for associating those users with said identificationaddress to permit communication to be established between those usersand the cellular telephone system via the server terminal.

Preferably the telephone system further comprises a plurality ofinterface systems each for providing a communication path between saidtransceiver and a switching network within a respective region, theswitching network being connected to said telephone network andconnectable to at least one of said interface systems when the vehicleis located in the region corresponding to that interface system therebyproviding a communication path between said transceiver and saidtelephone network, and control apparatus operable to select which one ofsaid interface systems should provide the communication path to thetransceiver when the vehicle is located in the regions corresponding toa plurality of interface systems.

Conveniently the location data base is connected to said telephonenetwork and is accessible to enable said network to locate each of saidaccepted users and thereby enable bi-directional communication betweensaid telephone network and each of said identified users.

Advantageously the control apparatus is further operable to controlsimultaneously the handover of said established communication when thevehicle moves from a first one of said regions to a second one of saidregions.

According to the present invention there is also provided a method ofoperating a telephone system within a vehicle to enable a plurality ofusers to simultaneously communicate with a ground based cellulartelephone system, which method comprises establishing a fixed connectionthrough a plurality of user terminals distributed on board the vehicleto a server terminal having an identification address, establishing aconnection between said server terminal and an onboard transceiver,identifying users of the cellular telephone system when their identitiesare accepted by respective user terminals, and associating identifiedusers with said identification address to permit simultaneouscommunication to be established between those users and the cellulartelephone system via the server terminal.

The vehicle may suitably be an aircraft, train or boat.

An embodiment of the invention will now be described hereinafter by wayof example only and with reference to the accompanying drawings inwhich:

FIG. 1 is a schematic view of a telephone communication system.

FIG. 2 is a schematic view of the vehicle telephone systems.

FIG. 3 schematically shows the aircraft in transit.

In the drawings like reference numerals refer to like parts.

The telephone system of this example enables subscribers to a cellularmobile telephone system to use telephones within an aircraft withoutcausing interference with the aircraft equipment. The system isparticularly applicable to subscribers to a known GSM/DCS network inwhich the user has a SIM card which the user may locate in a receptor ina phone to use the services available to him. The system may however beused with any mobile telephone system.

In the general scheme shown in FIG. 1 a plurality of users within anaircraft 10 are able to transmit or receive telephone messages through atransceiver located within the aircraft 10 which communicates via asatellite 12 to a ground earth station 14 using standard E1-link (CEPTE1) links 11 and 13. The ground earth station communicates through aninternet protocol (IP) (WAN=Wide Area Network) to a mobile switchingcentre (MSC) linked to a public service telephone network (PSTN). Theoperation of the mobile switching centre, ground earth station 14, andpublic switching telephone network are conventional in establishedcellular telephone networks.

The IP system 16 is integrated into the conventional cellular networktopology as one part of the network structure. It is one alternativemedium to link the mobile traffic from one location to another. At GESthe GI signal is converted into IP traffic.

FIG. 2 illustrates the aircraft telephone system 20 in more detail. Thetransmission and receipt of telephone message to and from the aircraft10 are handled by a transceiver which in the example is an aeronauticalearth station (AES). The aeronautical earth station communicates with asatellite 12 via E1 link 11 in a conventional way.

The aeronautical earth station is connected to a server terminal 23 suchas a PC server terminal via a fixed connection 22 which may be a CEPT-E12 Mbit fixed connection.

The PC has software which controls the mobile telephones 25 which aredistributed throughout the aircraft 10. Each mobile telephone (or userterminal) is connected via a fixed connection 26 such as an RS-232serial bus or universal serial bus (USB). The actual RS-232/USB networkcan be built by using twisted pair, fibre links or tiered starconnections.

By connecting the user terminals to the server PC and transceiver 21 viafixed links RF interference is avoided. In order to ensure that no RFinterference is created aircraft mobiles are provided which arepermanently connected via connector 26 to the USB and which have no GSMRF emitting antenna. Passengers put their own SIM cards or otheridentifier in a receptor in the phone.

By inserting the SIM card into the aircraft mobile or by connecting theuser's own mobile the user indicates when he wishes to use the telephonesystem so that he is identified by his own telephone number. Thisenables the user to be contacted in the aircraft and to utilise theservices which are normally available and also allows the user to beidentified for billing.

The mobile telephones 25 are connected into an Intranet cluster in theaircraft mobile network. When a user places his SIM card into theaircraft mobile telephone 25, or the telephone is connected to thetransceiver via the PC server terminal and can thereby communicate withthe ground based telephone network via satellite link. The mobileswitching centre which is part of the telephone network is updated withthe SIM identity. The cellular network thereafter identifies that thatthe user is in the aircraft.

The server PC 23 has its own identification address which is equivalentto the address stored in the visitor location register (VLR) database ina conventional mobile switching centre (MSC). The database could be inany suitable form and stored at any suitable unit; in this example it isstored in an Intranet location register (ILR) database. The Intranetlocation register database is updated when the SIM card is replaced by auser in the aircraft so that the mobile has a new location area code(LAC). Each aircraft mobile network (AMNW) forms one location area andusers in the aircraft are always associated with that area code whenconnected in the aircraft.

The provision of an Intranet mobile cluster whereby a plurality of usersare associated with a single IP address allows the handover of calls tobe carried out more conveniently. For example and with reference to FIG.3 the Inmarsat satellite system has at least three satellites 30 inorbit each of which covers a certain region or area over the globe 32.One handover area is above the Norwegian sea. As an aircraft moves fromone region to another calls currently being made on board the aircraftmust be handed over from one satellite and its associated ground earthstation 14 to the next satellite and its associated ground earthstation. The new routing ground earth station therefore has to beselected in accordance with the position of the aircraft. The telephonesystem therefore selects which one of the satellites and ground earthstations should provide the communication path to the transceiver whenthe aircraft is located in regions corresponding to more than onesatellite to provide the strongest signal. As the aircraft moves fromone region to another the IP address of the aeronautical mobile networkremains the same. This minimises the chance that the short satellitelink timeout, which affects calls to and from the aircraft, results incalls being dropped.

It will be appreciated that the use of the fixed connection in theaircraft telephone system prevents interference with the aircraftequipment. Furthermore the use of the described aircraft telephonesystem allows many users to make simultaneous calls to or from theaircraft.

The invention is not limited to the details of the foregoing example.

1. A telephone system for a vehicle comprising: a vehicle transceiver, on board said vehicle, and connectable to a cellular telephone network for bi-directional communication therewith; a server terminal, on board said vehicle, connected to said transceiver and having an identification address; a plurality of user terminals, distributed on board the vehicle, each capable of accepting an identity of a user of the cellular telephone system and each connected to said server terminal whereby a plurality of users may communicate simultaneously with said network via the server terminal; a location data base for identifying users of the cellular telephone system when their identifies are accepted by respective user terminals and for associating those users with said identification address to permit communication to be established between those users and the cellular telephone system via the server terminal; a plurality of interface systems each for providing a communication path between said transceiver and a switching network within a respective region, the switching network being connected to said telephone network and connectable to at least one of said interface systems when the vehicle is located in the region corresponding to that interface system thereby providing a communication path between said transceiver and said telephone network; and control apparatus operable to select which one of said interface systems should provide the communication path to the transceiver when the vehicle is located in the regions corresponding to a plurality of interface systems, the control apparatus being further operable to control simultaneously the handover of said established communication when the vehicle moves from a first one of the said regions to a second one of said regions, wherein said identification address remains unaltered as said vehicle moves from said first to said second respective regions.
 2. A telephone system according to claim 1 in which said location data base is connected to said telephone network and is accessible to enable said network to locate each of said accepted users and thereby enable bi-directional communication between said telephone network and each of said identified users.
 3. A telephone system according to claim 1 wherein said telephone system allows bi-directional communication between each user terminal in said vehicle and said telephone network.
 4. A telephone system according to claim 1 wherein each said interface system comprises a server satellite and at least one associated ground earth station.
 5. A telephone system according to claim 1 wherein said vehicle transceiver comprises a aeronautical earth station for bi-directional communication via satellite to a ground earth station which is connectable to the telephone network.
 6. A telephone system according to claim 1 wherein said location database is stored in a mobile switching centre.
 7. A telephone system according to claim 1 wherein said user terminal is connected to said server terminal via a first fixed connection and said server terminal is connected to said vehicle transceiver via a second fixed connection.
 8. A telephone system according to claim 7 wherein said first fixed connection is RS-232 serial bus or USB.
 9. A telephone system according to claim 7 wherein said first fixed connection is a universal serial bus (USB).
 10. A telephone system according to claim 7 wherein said second fixed connection is a CEPT-E 1 connection.
 11. A telephone system according to claim 1 wherein said user terminal comprises a cellular phone unit provided with an identification receptor for a subscription identifier of a user of the cellular telephone system.
 12. A telephone system according to claim 11 in which the identifier is a SIM card or Smart Card.
 13. A telephone system according to claim 1 wherein said user terminal comprises a phone receptor for receiving a user cellular phone.
 14. A telephone system according to claim 13 wherein said user cellular phone is adapted to deactivate radio transmission by the cellular phone when said cellular phone is connected to said phone receptor.
 15. A telephone system according to claim 1 wherein said server terminal comprises a personal computer (PC).
 16. A telephone system according to claim 1 wherein said location database identifies which user of the cellular telephone system is connected to a user terminal by a subscription identifier.
 17. A telephone system according to claim 1 wherein said switching network and control apparatus comprise an internet network.
 18. A telephone system according to claim 17 wherein said location database is an Intranet location register.
 19. A telephone system according to claim 1 wherein the vehicles is an aircraft.
 20. A method of operating a telephone system within a vehicle to enable a plurality of users to simultaneously communicate with a ground base cellular telephone system, which method comprises: establishing a fixed connection through a plurality of user terminals distributed on board the vehicle to a server terminal having an identification address; establishing a connection between said server terminal and an onboard transceiver; identifying users of the cellular telephone system wherein their identifies are accepted by respective user terminals; associating identified users with said identification address to permit simultaneous communication to be established between those users and the cellular telephone system via the server terminal; establishing a communication path between said transceiver and a switching network via a satellite and associated ground station when said vehicle is in a respective region wherein said switching network is connected to said cellular telephone system; selecting which satellite should provide a communication path to the transceiver when the vehicle is located in a region corresponding to a plurality of satellites; and controlling simultaneously the handover of said established connection when the vehicle moves from a first one of said respective regions to a second one of said respective regions, wherein said identification address remains unaltered as said vehicle moves from said first to said second respective regions.
 21. A method according to claim 20, wherein the vehicle is an aircraft. 